Combustion apparatus



Sept. 3, 1963 H. CLARE COMBUSTION APPARATUS 5 Sheets-Sheet 1 Filed June 20, 1960 Inventor y K/ar-a/d (liar-e M kWh/11214 vb/W Attorney Sept. 3, 1963 H. CLARE 3,102,393

COMBUSTION APPARATUS Filed June 20. 1960 3; Sireg3;s -Sh9et 2- Inventor Haw/d Czme Sept. 3, 1963 H. CLARE 3,

COMBUSTION APPARATUS Filed June 20, 1960 3 Sheets-Sheet 3 FIG. 4.

FIG. 5

Inventor B Harp/d Clay-e United States Patent 3,102,393 COMBUTION APPARATUS Harold Clare, Farnhorough, England, assignor to Power Jets (Research and Development) Limited, London,

England, a British company Filed June 20, 1960, Ser. No. 37,392 Claims priority, application Great Britain June 23, 1959 4 Claims. (Cl. 60-39.74)

This invention relates to combustion apparatus for the continuous combustion of liquid fuel.

The invention is primarily concerned with combustion apparatus for gas turbine plant. In conventional plant of this kind fuel is continuously supplied into a combustion chamber to which is fed a supply of compressed air, and the effluent, after combustion of the fuel, is expanded through a gas turbine. Various means have been proposed for supplying the fuel into the combustion chamber and one of these consists of a fuel-distributing disc rotatably mounted in the chamber, and means for introducing liquid fuel on to the side face of the disc so that, on rotation thereof, fuel is thrown off the disc as a sheet of fuel. The fuel sheet so produced is atomised by a high velocity air stream as it leaves the disc face. This arrangement forms the subject of copending United States patent application Serial No. 647,918 Probert et al., filed March 22, 1957.

Such an arrangement has advantages in continuous combustion plant, in particular gas turbine plant, in that the normal diffuser section of the combustion chamber can then be omitted which results in a reduction in the overall axial length of the plant.

However, to get satisfactory atomisation of the fuel in such a system the major part of the fuel supplied should be thrown off at the periphery of the fuel-distributing disc as a coherent sheet which is subjected to a shattering action by the high velocity air stream. To this end, it is necessary that the fuel should flow radially outwards on the side face of the rotating disc and, in the interests of efficiency, it is clearly desirable that such flow should be as even and uniform as is practical. Some di'tficulty has been experienced in achieving this desirable flow condition, since when fuel is fed on to the disc face through an axially facing opening therein, it has been found that there is a tendency for a proportion of the fuel to be discharged axially into the combustion space instead of flowing onto the disc face and accepting the rotary motion of the disc.

According to the present invention combustion ap paratus comprises a rotatably mounted fuel-distributing disc and means for introducing liquid fuel onto a side face of the disc with a swirling motion about the axis of rotation of the disc.

The fuel may be swirled either in the direction of rotation of the disc or in the opposite sense.

According to a feature of the invention the side face of the disc is formed with a coaxial recess having mounted therein a swirler, means being provided for introducing liquid fuel into the recess so that it flows through the swirler onto the face of the disc. The junction between the radially outer wall of the recess and the side face of the disc may be formed as a weir with a smoothly curved surface.

In this way the fuel flows over the weir with a swirling motion with respect to the axis of rotation of the disc and adheres to and accepts the rotary motion of the face of the disc so that it is flung off the periphery thereof as a coherent sheet.

In order that the invention may be better understood, two embodiments thereof will now be described with reference to the accompanying drawings, of which:

FIGURE 1 isa part axial-section of a gas turbine com- Patented Sept. 3, 1963 ice bustion chamber, the final stage of an axial flow compressor and a part of a gas turbine together with the interconnecting shaft also being shown.

FIGURE 2 is an enlarged view of part of FIGURE 1.

FIGURE 3 is a cross-section of the view shown in FIGURE 2 taken along the line lI-I-III.

FIGURE 4 is a view in axial cross section of a modified form of part of the fuel disc shown in FIGURE 2.

FIGURE 5 is a section on the line V-V of FIG- URE 4.

FIGURE 1 shows part of a gas turbine plant which is generally similar to that described and illustrated in copending U.S. patent application Serial No. 828,085, Deacon et al., filed July 20, 1959, now Patent No. 3,020,718. The plant comprises an axial flow compressor, an annular combustion chamber 2 and an axial flow turbine 3, the rotors of the compressor and turbine being mounted on a common two-part shaft 4. The compressor is arranged to supply compressed air through an annular inlet duct 2a into the combustion chamber 2 from which combustion products discharge into the turbine 3, the rotor of which is thereby driven, and drives the rotor of compressor through the shaft 4.

The combustion zone of the combustion chamber 2 is defined externally by a flame tube outer wall 5 spaced from the outer casing wall 6 of the combustion chamber and forming therewith a coolant passage 7. The combustion zone has a radially inner wall comprising two skins 8 and 9 spaced apart to provide a passage 10 for the flow of coolant fluid therebetween. The upstream end wall of the combustion zone is formed by the downstream face of a fuel-distributing disc 11 which is mounted for rotation on the axis of the plant with its periphery lying adjacent to the air inlet to the combustion chamber, and the face extending transversely to the direction of air flow through the inlet. The disc 11 is supported on a sleeve 12 which is mounted on the shaft 4 so as to rotate therewith in the sense indicated by the arrow A in FIGURE 3. The face of disc 11 has formed therein a coaxial annular recess or trough 13, the radially outer wall of which has a face which is contiguous with the face of the disc 11, the junction between these two faces being formed as a weir by a. smoothly curved surface 13a.

The disc 11 and the sleeve 12 define within them an annular gallery 14 (see FIGURE 2), while clamped between them there is an annular swirler member 15. The gallery communicates with the recess 13 by a series of ports 16 in the sleeve, an annular chamber 17 and a series of slots 15a in the swirler member, these slots being inclined to the radial direction as shown in FIG- URE 3. The gallery 14 is provided with a series of circumferentially spaced vanes 18 disposed between ports 16.

The :fuel inlet to the combustion chamber is provided by a fuel pipe 20 which extends across the annular duct 2a and terminates in an annular gallery 21 which is defined between an annular channel member 22 and a partconical wall 23. The wall 23 forms with a further partconical wall 24, a channel 25 which communicates with the gallery 21 by way of apertures 26 and with the annular gallery 14 by way of apertures 27.

In operation the compressor 2 directs air under pressure through annular duct 2a substantially without diffusion and through flame stabilising means 30 (which may be of the type shown in either of the copending applications referred to), axially across the periphery of the disc into the combustion zone of combustion chamber 2. Fuel passes through the fuel pipe 20 into the annular gallery 21 and into the annular channel 25 through the apertures 26. From the channel 25 the fuel passes through ports 27 into the gallery 14. The disc is rotated at the speed of the shaft 4 and fuel trapped between vanes 18 is forced under centrifugal action at increased pressure through ports 16 and chamber 17 into the swirl slots 15a in member 15. The inclined slots 15a impart to the fuel a radially outwands swirling motion in the same rotational sense as that of the disc 11. On the outlet, downstream side of the slots 15a the swirling fuel passes over the weir 13a, and on account of its swirling motion tends to adhere to [the face of the the disc 11 and accept the rotary motion thereof instead of being discharged axially into the combustion zone. As in the prior applications, the rate of fuel supply is so related to the speed of rotation of the disc that the fuel is flung off the disc periphery as a coherent sheet (as opposed to an atomized spray) which is shattered by the flow of air into the combustion zone.

As an alternative to the construction described above, the required rotational component of motion may be imparted to the fuel in the manner described with reference to FIGURES 4 and 5 which show a part only of the fueldistributing disc 11 adjacent the recess 13 and weir 13a, the disc 11 in this case being integral with the supporting sleeve 12. The fuel is supplied to the downstream side face of the disc by way of an annular gallery 31 to which it is led, as before, by an annular channel 25 and ports 27 disposed within the hub of the disc 11. The peripheral wall of the gallery 31 is defined by an insert 32 in the fuel disc which carries a series of spaced vanes 33, the spaces bet-ween which communicate with a number of axially extending ducts 34 extending within the disc hub into the recess 13. The ducts 34 communicate with a series of swirl channels 35a formed in the outer periphery of an annular member 35 secured to the disc within the recess. Between the member 35 and the weir 13a, the radially inwardly facing wall of the recess is formed with a shallow annular depression 36, for example, 0.02 inch in depth. As shown the channels 35a are inclined to the axial direction, and, for preference are made part helical.

In operation, fuel is supplied through the ports 27 into the gallery 31, 'the vanes 33, which rotate as one with the disc 11, giving the fuel a centrifugal pressure head and forcing it through ducts 34 and thence through swirl channels 35a. The latter impart a swirl motion to the fuel in the same sense as that of the disc and this swirl motion is preserved by causing the fuel to leave these channels and impinge on the inclined surface of the depression 36 which is designed to minimise the deleterious effect which might result if the fuel ware passed directly from swirl channels on to a plane wall surface, i.e., of a cylinder. From the depresion 36, the fuel flows to the weir 13a and having accepted a rotational component of motion flows smoothly on to the face of disc 11 with a minimum degree of disturbance.

In both of the embodiments described, the fuel is swirled in the direction of rotation of the disc 11. However the fuel may be caused to adhere to the disc by swirling it in the opposite sense to the direction or rotation, in which case the slots a or the channels 35a, as the case may be, will be inclined in the opposite sense to that shown in the drawings.

If the fuel is swirled in the opposite sense to the direction of rotation of the disc, the flow path followed by the fuel across the disc face will be appreciably longer (possibly by a factor of 1.5) than the path followed by the fuel when swirled in the direction of rotation. Thus by fitting a suitable swirler, the rsidence time of the fuel on the disc face can be selected according to the degree of evaporation required from the disc face. This is important in keeping the running temperature of the disc down to an acceptable value.

The above-described embodiments of the invention incorporate the system of cooling the double walls, 8, 9 of the combustion chamber as described in patent application Serial No. 828,085, air being supplied to the passage 10 through conduit 28, and ports 29 in the sleeve 12. The [fuel distributing disc itself is slightly coned to assist fuel distribution and carries paddles 19 to increase turbulence in the combustion zone. If desired, the fuel supply system as described in the above example may be modified to accord with the arrangement disclosed in patnt application Serial No. 647,918 in which fuel is led to the disc by way of a fuel conduit provided within the hollow rotor shaft.

Although the invention has been described in relation to a main combustion chamber, it may be applied equally to a reheat combustion chamber of an aircraft gas turbine jet propulsion engine.

I claim:

1. Combustion apparatus comprising an annular axially extending outer wall externally defining a combustion zone; a fuel-distributing disc mounted for rotation coaxially with respect to said wall at one end of the combustion zone, said disc having its periphery spaced inwardly from said wall :to define therewith a generally axially facing air inlet, and a side face extending generally transversely to the direction of fiow through said inlet and formed with a coaxial recess, the junction between the radially outer face of the recess and said side face being formed as a smoothly curved weir; a swirler mounted within said recess for rotation with the disc, said swirler being formed with helically-extending apertures inclined axially and means for supplying liquid fuel under pressure to flow through the swirler into the recess and over the weir on to the face of the disc at such a rate in relation to the speed of rotation of the disc that the fuel is thrown off the periphery of the disc across the inlet as a sheet of fuel.

2. Combustion apparatus according to claim 1 wherein the helically extending apertures of the swirler are arranged so that the fuel flows therethrough and is discharged therefrom oppositely to the direction of rotation of the disc.

3. Combustion apparatus according to claim 1 wherein said radially outer wall is formed with an annular depression between the swirler and the weir.

4. Combustion apparatus according to claim 1 wherein said side face of the disc defines said combustion zone at its inlet end.

References Cited in the file of this patent UNITED STATES PATENTS 1,418,444 Josephs June 6, 192.2 1,672,064 Holland June 5, 1928 2,280,638 Rulf Apr. 21, 1942 2,547,959 Miller Apr. 10, 1951 2,705,401 Allen Apr. 5, 1955 2,938,345 Perle May 31, 1960 2,981,066 Johnson Apr. 25, 1961 3,020,718 Deacon et 'al. Feb. 13, 1962 FOREIGN PATENTS 378,309 Great Britain Aug. 11, 1932 

1. COMBUSTION APPARATUS COMPRISING AN ANNULAR AXIALLY EXTENDING OUTER WALL EXTERNALLY DEFINING A COMBUSTION ZONE; A FUEL-DISTRIBUTING DISC MOUNTED FOR ROTATION COAXIALLY WITH RESPECT TO SAID WALL AT ONE END OF THE COMBUSTION ZONE, SAID DISC HAVING ITS PERIPHERY SPACED INWARDLY FROM SAID WALL TO DEFINE THEREWITH A GENERALLY AXIALLY FACING AIR INLET, AND A SIDE FACE EXTENDING GENERALLY TRANSVERSELY TO THE DIRECTION OF FLOW THROUGH SAID INLET AND FORMED WITH A COAXIAL RECESS, THE JUNCTION BETWEEN THE RADIALLY OUTER FACE OF THE RECESS AND SAID SIDE FACE BEING FORMED AS A SMOOTHLY CURVED WEIR; A SWIRLER MOUNTED WITHIN SAID RECESS FOR ROTATION WITH THE DISC, SAID SWIRLER 